This disclosure relates to resource management in data processing systems and more particularly to memory management by an operating system which controls a data processing system.
An operating system (OS), such as iOS or OS X from Apple Inc. or Microsoft Windows from Microsoft, is a collection of software that manages device hardware resources and provides common services for computer programs such as application software. Application software can be considered to be the computer program that causes a computer or other data processing system to perform useful tasks in response to user requests or other requests or other inputs. A specific instance of application software is called a software application, application program, application or app, which are used interchangeably herein. Application programs usually require an operating system to function.
As more and more apps and services are becoming available for small or mobile devices (e.g., a smartphone), the number of applications running at the same time in a single device has increased significantly. Moreover, many of these applications are not terminated or quit by a user after a user finishes using them so they continue to run and therefore continue to use system resources such as memory (e.g. volatile memory such as DRAM) even when they are no longer being used. Furthermore, idle background and foreground applications, while they may not use processing or computation resources, such as one or more microprocessors, they often use memory resources such as RAM while they are idle and not in use. These multiple applications or processes in the same device compete with each other by sharing the same memory resources and computation resources embedded within a device, and the operating system performs resource management, such as memory management, to deal with resource contention in concurrent computing. Memory management to control use of memory by running or idle applications has included techniques to terminate applications based on one or more indications of use of memory (e.g. DRAM) in a data processing system. U.S. Pat. Nos. 7,827,358 and 8,892,827 and published U.S. patent application numbers 2013/0332936 and 2013/0326166 describe examples of such techniques that also included other techniques such as deleting caches.